Pumping sewer into a septic tank. Bad idea?

[4570Man]

I’m working on a on a job now where a house is being built and they want to use an existing system. They planned on doing this from the start and the existing system was designed and permitted for the load so no problems there. But there’s not enough fall to gravity drain it. I’ve done sewer pumps before but they either pumped effluent into a leech field or they pumped raw sewer into a city sewer. I’ve never pumped raw sewer into a septic tank before. So the reason for concern is will a sudden surge of say 20-50 gallons into the tank at one time cause any problems into the septic tank?

 

[Jchonline]

Can you do it in smaller amounts over a few days? If so that would mimic actual use.

 

[4570Man]

Can you do it in smaller amounts over a few days? If so that would mimic actual use.

I could make the dosing cycle whatever I want but the smaller it is the more frequently the pump will cycle.

 

[JJT]

20 - 50 gallons at a time into a 1000 gallon or bigger tank is not going to cause an issue. Lots of houses have basement bathrooms and laundry rooms with grinder pumps pumping up to a septic tank.

 

[4570Man]

20 - 50 gallons at a time into a 1000 gallon or bigger tank is not going to cause an issue. Lots of houses have basement bathrooms and laundry rooms with grinder pumps pumping up to a septic tank.

I haven’t looked at the original build specs but it was permitted for 4 bedrooms. So it’ll be minimum 1000 gallons.

 

[Jchonline]

My dosed septic for 3 bedrooms is 75gal 4 times a day. SOrry I thought you meant a 1 time drain of 20-50 gal.

 

[RjCorazza]

My tub holds just under 80 gallons to the overflow. After 23 years on a septic system we have never had a problem. I have also periodically dumped 40 gallons of sewage from an RV without issue.

 

[4570Man]

My dosed septic for 3 bedrooms is 75gal 4 times a day. SOrry I thought you meant a 1 time drain of 20-50 gal.

But that’s pumping effluent into a leech field isn’t it?

 

[Rustyiron]

Good question
Are you gravity to a pump vault then forced to the existing tank? A 300 gallon (?) pump vault would keep the pump outside and be able to act as a "buffer" during heavy use times.
I've never worked on something like this, but as I remember, there's a good bit of floats and alarms involved so that a (shitty) problem in the house doesn't occur. Does your town or county have requirements (advice) for this set up?

 

[4570Man]

Good question
Are you gravity to a pump vault then forced to the existing tank? A 300 gallon (?) pump vault would keep the pump outside and be able to act as a "buffer" during heavy use times.
I've never worked on something like this, but as I remember, there's a good bit of floats and alarms involved so that a (shitty) problem in the house doesn't occur. Does your town or county have requirements (advice) for this set up?

Yes that’s how it’ll work. The local septic inspector is incredibly unhelpful.